Shaped load modulation in near field communications (NFC) device

ABSTRACT

A method and apparatus is disclosed to compensate for overshoot and/or undershoot in a transmission sequence by shaping the transmission sequence according to a shaping envelope to lengthen its rise time and/or fall time to provide a modified transmission sequence. The shaping envelope may represent a trigonometric function, a polynomial function, a piecewise function or any other function that lengthens the rise time and/or the fall time of the transmission sequence. The modified transmission sequence adjusts an impedance of an antenna to load modulate a carrier wave that is inductively coupled to it.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.13/271,553, filed Oct. 12, 2011, now U.S. Pat. No. 8,831,515 which isincorporated herein by reference in its entirety for all purposes.

BACKGROUND

1. Field of Invention

The invention relates to near field communications (NFC), and morespecifically to shaped load modulation in a NFC device.

2. Related Art

Near field communication (NFC) devices are being integrated into mobiledevices, such as smartphones for example, to facilitate the use of thesemobile devices in conducting daily transactions. For example, instead ofcarrying numerous credit cards, the credit information provided by thesecredit cards can be loaded into a NFC device and stored therein to beused as needed. The NFC device is simply tapped to a credit cardterminal to relay the credit information to it to complete atransaction. As another example, a ticket writing system, such as thoseused in bus and train terminals, may simply write ticket fareinformation onto the NFC device instead of providing a paper ticket to apassenger. The passenger simply taps the NFC device to a reader to ridethe bus or the train without the use of the paper ticket.

Conventionally, the credit card information and the ticket fareinformation are stored onto a NFC device that operates in a target, ortag, mode of operation. This NFC device communicates the information toanother NFC device using the information to modulate an impedance acrossits antenna terminals which is then detected by the other NFC device.This communications scheme is commonly referred to as load modulation.The load modulation should be carefully controlled to preventintroduction of unwanted noise into the communication which mayinterfere with the communication of the information as well as othercommunications between other communications devices.

Thus, there is a need to control load modulation in a NFC device thatovercomes the shortcomings described above. Further aspects andadvantages of the present invention will become apparent from thedetailed description that follows.

BRIEF DESCRIPTION OF THE DRAWINGS/FIGURES

The present invention is described with reference to the accompanyingdrawings. In the drawings, like reference numbers indicate identical orfunctionally similar elements.

FIG. 1 illustrates a block diagram of a NFC environment according to anexemplary embodiment of the invention;

FIG. 2 illustrates a block diagram of a conventional NFC device that maybe implemented within the NFC environment according to an exemplaryembodiment of the invention;

FIG. 3 graphically illustrates a conventional transmitted communicationssignal that is provided by the conventional NFC device;

FIG. 4 illustrates a block diagram of a NFC device that may beimplemented within the NFC environment according to an exemplaryembodiment of the invention;

FIG. 5 illustrates a block diagram of an envelope shaping module thatmay be implemented within the NFC device according to an exemplaryembodiment of the invention; and

FIG. 6 graphically illustrates a transmitted communications signal thatis provided by the NFC device according to an exemplary embodiment ofthe present invention.

The present invention will now be described with reference to theaccompanying drawings. In the drawings, like reference numbers generallyindicate identical, functionally similar, and/or structurally similarelements. The drawing in which an element first appears is indicated bythe leftmost digit(s) in the reference number.

DETAILED DESCRIPTION OF THE INVENTION

The following Detailed Description refers to accompanying drawings toillustrate exemplary embodiments consistent with the invention.References in the Detailed Description to “one exemplary embodiment,”“an exemplary embodiment,” “an example exemplary embodiment,” etc.,indicate that the exemplary embodiment described may include aparticular feature, structure, or characteristic, but every exemplaryembodiment may not necessarily include the particular feature,structure, or characteristic. Moreover, such phrases are not necessarilyreferring to the same exemplary embodiment. Further, when a particularfeature, structure, or characteristic is described in connection with anexemplary embodiment, it is within the knowledge of those skilled in therelevant art(s) to affect such feature, structure, or characteristic inconnection with other exemplary embodiments whether or not explicitlydescribed.

The exemplary embodiments described herein are provided for illustrativepurposes, and are not limiting. Other exemplary embodiments arepossible, and modifications may be made to the exemplary embodimentswithin the spirit and scope of the invention. Therefore, the DetailedDescription is not meant to limit the invention. Rather, the scope ofthe invention is defined only in accordance with the following claimsand their equivalents.

Embodiments of the invention may be implemented in hardware, firmware,software, or any combination thereof. Embodiments of the invention mayalso be implemented as instructions stored on a machine-readable medium,which may be read and executed by one or more processors. Amachine-readable medium may include any mechanism for storing ortransmitting information in a form readable by a machine (e.g., acomputing device). For example, a machine-readable medium may includeread only memory (ROM); random access memory (RAM); magnetic diskstorage media; optical storage media; flash memory devices; electrical,optical, acoustical or other forms of propagated signals (e.g., carrierwaves, infrared signals, digital signals, etc.), and others. Further,firmware, software, routines, instructions may be described herein asperforming certain actions. However, it should be appreciated that suchdescriptions are merely for convenience and that such actions in factresult from computing devices, processors, controllers, or other devicesexecuting the firmware, software, routines, instructions, etc.

The following Detailed Description of the exemplary embodiments will sofully reveal the general nature of the invention that others can, byapplying knowledge of those skilled in relevant art(s), readily modifyand/or adapt for various applications such exemplary embodiments,without undue experimentation, without departing from the spirit andscope of the present invention. Therefore, such adaptations andmodifications are intended to be within the meaning and plurality ofequivalents of the exemplary embodiments based upon the teaching andguidance presented herein. It is to be understood that the phraseologyor terminology herein is for the purpose of description and not oflimitation, such that the terminology or phraseology of the presentspecification is to be interpreted by those skilled in relevant art(s)in light of the teachings herein.

Although, the description of the present invention is to be described interms of NFC, those skilled in the relevant art(s) will recognize thatthe present invention may be applicable to other communications that usethe near field and/or the far field without departing from the spiritand scope of the present invention. For example, although the presentinvention is to be described using NFC capable communication devices,those skilled in the relevant art(s) will recognize that functions ofthese NFC capable communication devices may be applicable to othercommunications devices that use the near field and/or the far fieldwithout departing from the spirit and scope of the present invention.

An Exemplary Near Field Communications (NFC) Environment

FIG. 1 illustrates a block diagram of a NFC environment according to anexemplary embodiment of the invention. A NFC environment 100 provideswireless communication of information, such as one or more commandsand/or data, among a first NFC device 102 and a second NFC device 104that are sufficiently proximate to each other. The first NFC device 102and/or the second NFC device 104 may be implemented as a standalone or adiscrete device or may be incorporated within or coupled to anotherelectrical device or host device such as a mobile telephone, a portablecomputing device, another computing device such as a personal, a laptop,or a desktop computer, a computer peripheral such as a printer, aportable audio and/or video player, a payment system, a ticket writingsystem such as a parking ticketing system, a bus ticketing system, atrain ticketing system or an entrance ticketing system to provide someexamples, or in a ticket reading system, a toy, a game, a poster,packaging, advertising material, a product inventory checking systemand/or any other suitable electronic device that will be apparent tothose skilled in the relevant art(s) without departing from the spiritand scope of the invention.

The first NFC device 102 and/or the second NFC device 104 interact witheach other to exchange the information, in a peer (P2P) communicationmode or a reader/writer (R/W) communication mode. In the P2Pcommunication mode, the first NFC device 102 and the second NFC device104 may be configured to operate according to an active communicationmode and/or a passive communication mode. The first NFC device 102modulates its corresponding information onto a first carrier wave,referred to as a modulated information communication, and generates afirst magnetic field by applying the modulated information communicationto the first antenna to provide a first information communication 152.The first NFC device 102 ceases to generate the first magnetic fieldafter transferring its corresponding information to the second NFCdevice 104 in the active communication mode. Alternatively, in thepassive communication mode, the first NFC device 102 continues to applythe first carrier wave without its corresponding information, referredto as an unmodulated information communication, to continue to providethe first information communication 152 once the information has beentransferred to the second NFC device 104.

The first NFC device 102 is sufficiently proximate to the second NFCdevice 104 such that the first information communication 152 isinductively coupled onto a second antenna of the second NFC device 104.The second NFC device 104 demodulates the first informationcommunication 152 to recover the information. The second NFC device 104may respond to the information by modulating its correspondinginformation onto a second carrier wave and generating a second magneticfield by applying this modulated information communication to the secondantenna to provide a second modulated information communication 154 inthe active communication mode. Alternatively, the second NFC device 104may respond to the information by modulating the second antenna with itscorresponding information to modulate the first carrier wave to providethe second modulated information communication 154 in the passivecommunication mode.

In the R/W communication mode, the first NFC device 102 is configured tooperate in an initiator, or reader, mode of operation and the second NFCdevice 104 is configured to operate in a target, or tag, mode ofoperation. The first NFC device 102 modulates its correspondinginformation onto the first carrier wave and generates the first magneticfield by applying the modulated information communication to the firstantenna to provide the first information communication 152. The firstNFC device 102 continues to apply the first carrier wave without itscorresponding information to continue to provide the first informationcommunication 152 once the information has been transferred to thesecond NFC device 104. The first NFC device 102 is sufficientlyproximate to the second NFC device 104 such that the first informationcommunication 152 is inductively coupled onto a second antenna of thesecond NFC device 104.

The second NFC device 104 derives or harvests power from the firstinformation communication 152 to recover, to process, and/or to providea response to the information. The second NFC device 104 demodulates thefirst information communication 152 to recover and/or to process theinformation. The second NFC device 104 may respond to the information bymodulating the second antenna with its corresponding information tomodulate the first carrier wave to provide the second modulatedinformation communication 154.

Further operations of the first NFC device 102 and/or the second NFCdevice 104 may be described in International Standard ISO/IE18092:2004(E), “Information Technology—Telecommunications andInformation Exchange Between Systems—Near Field Communication—Interfaceand Protocol (NFCIP-1),” published on Apr. 1, 2004 and InternationalStandard ISO/IE 21481:2005(E), “InformationTechnology—Telecommunications and Information Exchange BetweenSystems—Near Field Communication—Interface and Protocol-2 (NFCIP-2),”published on Jan. 15, 2005, each of which is incorporated by referenceherein in its entirety.

A Conventional NFC Device

FIG. 2 illustrates a block diagram of a conventional NFC device that maybe implemented within the NFC environment according to an exemplaryembodiment of the invention. A conventional NFC device 200 isconfigurable to operate in the target, or tag, mode of operation torecover, to process, and/or to provide a response to information fromanother NFC capable device, such as the first NFC device 102 or thesecond NFC device 104 to provide some examples. The conventional NFCdevice 200 includes an antenna module 202, a demodulator module 204, acontroller module 206, and a power harvesting module 208.

The antenna module 202 inductively receives a received communicationssignal 250 from the other NFC capable device to provide a recoveredcommunications signal 252. Typically, the received communications signal250 may include either the modulated information communication thatincludes information modulated onto a carrier wave and/or theunmodulated information communication that includes only the carrierwave.

The demodulator module 204 demodulates the recovered communicationssignal 252 using any suitable analog or digital modulation technique toprovide a recovered information sequence 254. The recovered informationsequence 254 may include information that is recovered from themodulated information communication. The suitable analog or digitalmodulation technique may include amplitude modulation (AM), frequencymodulation (FM), phase modulation (PM), phase shift keying (PSK),frequency shift keying (FSK), amplitude shift keying (ASK), quadratureamplitude modulation (QAM) and/or any other suitable modulationtechnique that will be apparent to those skilled in the relevant art(s)without departing from the spirit and scope of the present invention.

The controller module 206 controls overall operation and/orconfiguration of the conventional NFC device 200. The controller module206 transmits and/or receives information 256 to and/or from one or moredata storage devices such as one or more contactless transponders, oneor more contactless tags, one or more contactless smartcards, any othermachine-readable media that will be apparent to those skilled in therelevant art(s) without departing from the spirit and scope of theinvention, or any combination thereof. The other machine-readable mediamay include, but is not limited to, read only memory (ROM), randomaccess memory (RAM), magnetic disk storage media, optical storage media,flash memory devices, electrical, optical, acoustical or other forms ofpropagated signals such as carrier waves, infrared signals, digitalsignals to provide some examples. Additionally, the controller module206 may transmit and/or receive the information 256 to and/or from auser interface such as a touch-screen display, an alphanumeric keypad, amicrophone, a mouse, a speaker, any other suitable user interface thatwill be apparent to those skilled in the relevant art(s) withoutdeparting from the spirit and scope of the invention to provide someexamples. The controller module 206 may further transmit and/or receivethe information 256 to and/or from other electrical devices or hostdevices coupled to the conventional NFC device 200.

The controller module 206 may use the information 256 to control theoverall operation and/or configuration of the conventional NFC device200. Additionally, the controller module 206 may provide the recoveredinformation sequence 254 as the information 256 and/or provide theinformation 256 as a transmission sequence 258 for transmission toanother NFC capable device. The controller module 206 modulates thereceived communications signal 250 that is coupled onto the antennamodule 202 with the transmission sequence 258 to provide a transmittedcommunications signal 260. For example, the transmission sequence 258adjusts an impedance of the antenna module 202 to load modulate theunmodulated information communication inductively coupled onto theantenna module 202 with the transmission sequence 258.

Conventional Transmitted Communications Signal

FIG. 3 graphically illustrates a conventional transmitted communicationssignal that is provided by the conventional NFC device. The transmissionsequence 258 is in a form of logic values based on the binary numbersystem. The two symbols most commonly chosen to represent the two logicvalues taken on by binary symbols are binary zero and binary one. Acontroller module, such as the controller module 206, may encodeinformation using the binary zero and the binary one to provide thetransmission sequence 258. The binary one is represented by a symbol ofconstant amplitude for the duration of the symbol and the binary zero isrepresented by switching off the symbol.

Ideally, the controller module 206 modulates an amplitude of thereceived communications signal 250 in accordance with the transmissionsequence 258 to provide a transmitted communications signal 300. Thetransmission sequence 258 is used to adjust an impedance of the antennamodule 202 to be at a first impedance when the transmission sequence 258is the binary one and/or to be at a second impedance when thetransmission sequence 258 is the binary zero. The first impedance of theantenna module 202 causes the transmitted communications signal 300 tobe at a first level 350 when the transmission sequence 258 is the binaryone and/or the second impedance causes the transmitted communicationssignal 300 to be at a second level 352 when the transmission sequence258 is the binary zero.

However, a rise time required for the transmission sequence 258 totransition from the binary zero to the binary one may cause thetransmitted communications signal 260 to rise above, commonly referredto as an overshoot condition 354, the first level 350 after thetransmission sequence 258 has transitioned from the binary zero to thebinary one. In the overshoot condition 354, the transmittedcommunications signal 260 rises above the first level 350 and mayeventually settle to the first level 350. Similarly, a fall timerequired for the transmission sequence 258 to transition from the binaryone to the binary zero, may cause the transmitted communications signal260 to fall below, commonly referred to as an undershoot condition 356,the second level 352 after the transmission sequence 258 hastransitioned from the binary one to the binary zero. In the undershootcondition 356, the transmitted communications signal 260 falls below thesecond level 352 and may eventually settle to the second level 352.

Conventionally, the antenna module 202 is implemented using a resonantcircuit that includes an inductor and a capacitor that are configuredand arranged in either a series or a parallel configuration. The risingand/or falling of the transmission sequence 258 charges and/ordischarges the capacitor and/or the inductor. A rate at which thecapacitor charges and the inductor discharges is related to a rate atwhich the transmission sequence 258 transitions from the binary zero tothe binary one. When the transmission sequence 258 transitions from thebinary zero to the binary one too quickly, the capacitor charges at afaster rate than the inductor discharges which results in the overshootcondition 354. Similarly, a rate at which the capacitor discharges andthe inductor charges is related to a rate at which the transmissionsequence 258 transitions from the binary one to the binary zero. Whenthe transmission sequence 258 transitions from the binary one to thebinary zero too quickly, the capacitor discharges at a faster rate thanthe inductor charges which results in the undershoot condition 356. Theantenna module 202, as well as the conventional NFC device 200, may alsoinclude one or more unavoidable parasitic capacitances and/orinductances that may similarly be charged and/or discharged in responseto the transmission sequence 258 transitioning from the binary zero tothe binary one and/or from the binary one to the binary zero.

An Exemplary NFC Device

FIG. 4 illustrates a block diagram of a NFC device that may beimplemented within the NFC environment according to an exemplaryembodiment of the invention. A NFC device 400 is configurable to operatein the target, or tag, mode of operation to recover, to process, and/orto provide a response to information from another NFC capable device,such as the first NFC device 102 or the second NFC device 104 to providesome examples. The NFC device 400 lengthens a rise time and/or a falltime of its information to be transmitted to substantially reduceovershoot and/or undershoot when compared to the conventional NFC device200. The NFC device 400 includes the antenna module 202, the demodulatormodule 204, the controller module 206, the power harvesting module 208,and an envelope shaping module 402. The NFC device 400 may represent anexemplary embodiment of the first NFC device 102 and/or the second NFCdevice 104. The NFC device 400 shares many substantially similarfeatures as the conventional NFC device 200; therefore, only differencesbetween the conventional NFC device 200 and the NFC device 400 are to bediscussed below.

The controller module 206 may provide the information 256 as atransmission sequence 450 for transmission to another NFC capabledevice. The controller module 206 may encode the information 256according to an on-off signaling scheme, a non-return-to-zero (NRZ)scheme, a bipolar scheme, a Manchester code, or any other amplitude,frequency, and/or phase encoding scheme that will be apparent to thoseskilled in the relevant art(s) without departing from the spirit andscope of the present invention.

The envelope shaping module 402 modifies the transmission sequence 450to modify an envelope of a transmitted communications signal 452 toprovide a modified transmission sequence 454. The transmission sequence450 is used to modulate the received communications signal 250 that iscoupled onto the antenna module 202 to provide the transmittedcommunications signal 452. The envelope shaping module 402 modifies orshapes the transmission sequence 450 according to a shaping envelope tolengthen its rise time and/or fall time when compared to the rise timeand/or the fall time of the transmission sequence 258. This increase inthe rise time and/or the fall time of the transmission sequence 450substantially reduces overshoot and/or undershoot of the NFC device 400when compared to the conventional NFC device 200.

For example, the shaping envelope may represent a waveshaper thatapplies a fixed or variable mathematical function to the transmissionsequence 450 to substantially lengthen its rise time and/or fall timewhen compared to the rise time and/or the fall time of the transmissionsequence 258. Generally, the modified transmission sequence 454 may berepresented as:y(n)=f(x(n)),  (1)where y(n) represents the modified transmission sequence 454, x(n)represents the transmission sequence 450, and f(•) represents awaveshaping shaping function. The waveshaping shaping function mayrepresent a trigonometric function, a polynomial function, a piecewisefunction, or any other function that lengthens the rise time and/or thefall time of the transmission sequence 450 when compared to thetransmission sequence 258 that will be apparent to those skilled in therelevant art(s) without departing from the spirit and scope of thepresent invention. In an exemplary embodiment, the polynomial functionmay be represented as:

$\begin{matrix}{{{y(n)} = {\sum\limits_{n = 0}^{K}\;\frac{a_{n}}{{x(n)}^{n}}}},} & (2)\end{matrix}$where y(n) represents the modified transmission sequence 454, x(n)represents the transmission sequence 450, and a, represents any suitablegain coefficient.

Exemplary Envelope Shaping Module

FIG. 5 illustrates a block diagram of an envelope shaping module thatmay be implemented within the NFC device according to an exemplaryembodiment of the invention. A waveshaper 502 applies a wave shapingfunction to the transmission sequence 450 to lengthen its rise timeand/or fall time when compared to the rise time and/or the fall time ofthe transmission sequence 258. As shown in FIG. 5, the waveshaper 502 isconfigured and arranged to perform an inverse square function that maybe denoted as:

$\begin{matrix}{{{y(n)} = \frac{a_{2}}{{x(n)}^{2}}},} & (3)\end{matrix}$where y(n) represents the modified transmission sequence 454, x(n)represents the transmission sequence 450, and a₂ represents any suitablegain coefficient which is typically one. The waveshaper 502 includes aninverter 504, a multiplier 506, and a feedback resistor 508. Thewaveshaper 502 may represent an exemplary embodiment of the envelopeshaping module 402.

The inverter 504 inverts the transmission sequence 450 to provide themodified transmission sequence 454.

The multiplier 506 multiplies the modified transmission sequence 454with itself to provide a squared transmission sequence 550. Themultiplier 506 effectively raises the modified transmission sequence 454to a power of two or squares the modified transmission sequence 454 toprovide the squared transmission sequence 550.

The feedback resistor 508 provides the squared transmission sequence 550to the inverter 504 to result in the inverse square function.

Exemplary Transmitted Communications Signal

FIG. 6 graphically illustrates a transmitted communications signal thatis provided by the NFC device according to an exemplary embodiment ofthe present invention. The transmission sequence 450 is in a form oflogic values based on the binary number system. The two symbols mostcommonly chosen to represent the two logic values taken on by binarysymbols are binary zero and binary one. As shown in FIG. 6, a controllermodule, such as the controller module 206, may encode information usingthe binary zero and the binary one to provide the transmission sequence450. The binary one is represented by a symbol of constant amplitude forthe duration of the symbol and the binary zero is represented byswitching off the symbol.

An envelope shaping module, such as the envelope shaping module 402,modifies the transmission sequence 450 to provide the modifiedtransmission sequence 454. The envelope shaping module 402 modifies orshapes the transmission sequence 450 according to a shaping envelope tosubstantially lengthen its rise time and/or fall time when compared tothe rise time and/or the fall time of the transmission sequence 258.

The controller module 206 modulates the amplitude of the receivedcommunications signal 250 in accordance with the modified transmissionsequence 454 to provide the transmitted communications signal 452. Themodified transmission sequence 454 is used to adjust the impedance ofthe antenna module 202 to be at the first impedance when the modifiedtransmission sequence 454 is the binary one and/or to be at the secondimpedance when the modified transmission sequence 454 is the binaryzero. The first impedance of the antenna module 202 causes thetransmitted communications signal 452 to be at the first level 350 whenthe modified transmission sequence 454 is the binary one and/or thesecond impedance causes the transmitted communications signal 452 to beat the second level 352 when the modified transmission sequence 454 isthe binary zero.

As discussed above, the antenna module 202 is implemented using aresonant circuit that includes an inductor and a capacitor that areconfigured and arranged in either a series or a parallel configuration.The rising and/or falling of the modified transmission sequence 454charges and/or discharges the capacitor and/or the inductor. The longerrise time of the modified transmission sequence 454 allows more time forthe capacitor to charge and the inductor to discharge when the modifiedtransmission sequence 454 transitions from the binary zero to the binaryone. This longer rise time substantially reduces, or altogethereliminates, the overshoot condition 354. For example, the longer risetime allows to the inductor to be completely discharged before themodified transmission sequence 454 completes its transition from thebinary zero to the binary one. Similarly, the fall time of the modifiedtransmission sequence 454 allows more time for the capacitor todischarge and the inductor to charge when the modified transmissionsequence 454 transitions from the binary one to the binary zero. Thislonger rise time and/or fall time substantially reduces, or altogethereliminates, the undershoot condition 356. For example, the longer falltime allows to the capacitor to be completely discharged before themodified transmission sequence 454 completes its transition from thebinary one to the binary zero.

CONCLUSION

It is to be appreciated that the Detailed Description section, and notthe Abstract section, is intended to be used to interpret the claims.The Abstract section may set forth one or more, but not all exemplaryembodiments, of the present invention, and thus, are not intended tolimit the present invention and the appended claims in any way.

The present invention has been described above with the aid offunctional building blocks illustrating the implementation of specifiedfunctions and relationships thereof. The boundaries of these functionalbuilding blocks have been arbitrarily defined herein for the convenienceof the description. Alternate boundaries may be defined so long as thespecified functions and relationships thereof are appropriatelyperformed.

It will be apparent to those skilled in the relevant art(s) that varioustransitions in form and detail can be made therein without departingfrom the spirit and scope of the invention. Thus the present inventionshould not be limited by any of the above-described exemplaryembodiments, but should be defined only in accordance with the followingclaims and their equivalents.

What is claimed is:
 1. A near field communications (NFC) device,comprising: a controller circuit configured to provide a first sequenceof data; and an envelope shaping module, coupled to the controllercircuit, configured to: receive the first sequence of data, adjust arise time or a fall time of the first sequence of data to provide asecond sequence of data, and cause the second sequence of data to beload modulated onto a magnetic field to provide a transmittedcommunications signal for transmission to a second NFC device.
 2. TheNFC device of claim 1, wherein the envelope shaping module is configuredto increase the rise time or the fall time of the first sequence ofdata.
 3. The NFC device of claim 2, wherein the transmittedcommunications signal is characterized as having no substantialovershoot or no substantial undershoot.
 4. The NFC device of claim 1,wherein the envelope shaping module is configured to adjust the firstsequence of data according to a shaping envelope to adjust the rise timeor the fall time.
 5. The NFC device of claim 4, wherein the shapingenvelope comprises: a mathematical function.
 6. The NFC device of claim1, further comprising: an antenna module configured to load modulate thesecond sequence of data onto the magnetic field.
 7. The NFC device ofclaim 6, wherein the antenna module comprises: an impedance configuredto be adjusted by the second sequence of data to load modulate a carrierwave that is inductively coupled onto the antenna module from themagnetic field.
 8. The NFC device of claim 7, wherein the impedancecomprises: a first passive element configured to discharge before thesecond sequence of data transitions between a first state and a secondstate, and a second passive element configured to charge before thesecond sequence of data transitions between the first state and thesecond state.
 9. A near field communications (NFC) device, comprising:an envelope shaping module configured to adjust a rise time or a falltime of a first sequence of data to provide a second sequence of data,and an antenna module, coupled to the envelope shaping module,configured to: receive the second sequence of data, and load modulatethe second sequence of data onto a magnetic field for transmission to asecond NFC device.
 10. The NFC device of claim 9, wherein the envelopeshaping module is configured to increase the rise time or the fall timeof the first sequence of data.
 11. The NFC device of claim 9, whereinthe transmission is characterized as having no substantial overshoot orno substantial undershoot.
 12. The NFC device of claim 9, wherein theenvelope shaping module is configured to adjust the first sequence ofdata according to a shaping envelope to adjust the rise time or the falltime of the first sequence of data.
 13. The NFC device of claim 12,wherein the shaping envelope comprises: a mathematical function.
 14. TheNFC device of claim 9, wherein the antenna module comprises: animpedance configured to be adjusted by the second sequence of data toload modulate a carrier wave that is inductively coupled onto theantenna module from the magnetic field.
 15. The NFC device of claim 14,wherein the impedance comprises: a first passive element configured todischarge before the second sequence of data transitions between a firststate and a second state, and a second passive element configured tocharge before the second sequence of data transitions between the firststate and the second state.
 16. A near field communications (NFC)device, comprising: a controller circuit configured to provide a firstsequence of data; and an envelope shaping module, coupled to thecontroller circuit, configured to: receive the first sequence of data,shape the first sequence of data according to a mathematical function toprovide a second sequence of data, and cause the second sequence of datato be load modulated onto a magnetic field to provide a transmittedcommunications signal for transmission to a second NFC device, whereinthe mathematical function is configured to lessen overshoot orundershoot in the transmitted communications signal as compared to theovershoot or the undershoot in the transmitted communications signalthat would occur if the first sequence of data were load modulated ontothe magnetic field.
 17. The NFC device of claim 16, wherein the envelopeshaping module is further configured to increase a rise time or a falltime of the first sequence of data.
 18. The NFC device of claim 16,further comprising: an antenna module configured to load modulate thesecond sequence of data onto the magnetic field.
 19. The NFC device ofclaim 18, wherein the antenna module comprises: an impedance configuredto be adjusted by the second sequence of data to load modulate a carrierwave that is inductively coupled onto the antenna module from themagnetic field.
 20. The NFC device of claim 19, wherein the impedancecomprises: a first passive element configured to discharge before thesecond sequence of data transitions between a first state and a secondstate, and a second passive element configured to charge before thesecond sequence of data transitions between the first state and thesecond state.